The present invention relates to a vise, and more particularly to a hold-down device for movable jaw of a vise.
The hold-down device for movable jaw of a vise was described in the U.S. Pat. No. 2,880,638. As shown in FIG. 1, the hold-down device for movable jaw of a vise holds a work piece by making use of the bevel 48 of a driving block 46 to exert via a semi-spherical piece 50 a downward component force on the movable jaw member 40, which is therefore held down so as to keep the holding surface of the vise jaw 68 in a precise vertical position in relation to the surface of the vise stand.
Such hold-down device for movable jaw of a vise of the prior art is defective in design in that the neck 49 of the driving block 46 and the adjacent area thereof are subjected to a substantial bending stress, which is often responsible for the crack of the driving block 46, and that the hold-down device is apparently unable to initiate an effective hold-down action when the vise is holding the work piece 153 (as shown in dotted lines in FIG. 4) in a pulling manner. In other words, the hold-down device for movable jaw of a vise of the prior art works only when the vise is holding the work piece 153 in a compressing manner.